This invention relates to a vehicle leveling system which is provided with a compressor and a leveler unit for lifting a vehicle body by compressed air from the compressor.
It is known in the art to adjust the level of a vehicle body by feeding and discharging compressed air to and from a leveler unit which is mounted between sprung and unsprung mass of the vehicle. Compressed air is supplied to the leveler unit normally by means of a compressor which takes air from atmosphere. The air from atmosphere unavoidably contains moisture, which is condensed upon pressurization of air and causes troubles to the operation of the leveler unit if transferred thereinto along with compressed air.
In order to prevent moisture from being entrained in compressed air to be supplied to the leveler unit, it is known to provide between the compressor and leveler unit a moisture remover or air dryer, for example, from U.S. Pat. Nos. 3,667,775 and 3,784,220, which is filled with desiccant means such as silica gel or the like for separating and collecting moisture from compressed air. The air dryer of the latter patent removes moisture in the compressed air from the compressor in the pump-up phase of operation by adsorption on the desiccant, purging moisture from the desiccant by dry air in the exhaust phase of operation to permit regenerative repeated use of the desiccant.
However, under extremely humid conditions or in a case where air is compressed to a relatively high pressure, a large amount of water droplets is produced upon compression of intake air. Once a large amount of condensed water droplets is adsorbed on the desiccant, it becomes difficult to purge moisture sufficiently therefrom by contact with dry air in the regenerative stage and a substantial amount of moisture remains on the desiccant. If the dryer is repeatedly operated under such conditions, the desiccant soon becomes wet, resulting in an abrupt drop of its moisture adsorption capacity. Therefore, it has been general practice to resort to a heater for the purpose of accelerating the moisture purge from the desiccant in the regenerative stage or to replace the desiccant frequently.